Propeller with replaceable blades



May 12, 1964 R. B. LESH/ER PROPELLER WITH REPLACEABLE BLADES Filed Feb. 8, 1961 Royal 8. Les-her INVENTOR.

United States Patent 3,132,698 PROPELLER WITH REPLACEABLE BLADES Royal B. Lesher, 14526 Meridian Ave, Seattle, Wash. Filed Feb. S, 1961, Ser. No. 87,847 1 Claim. (Cl. 170173) This invention relates to a novel and useful propeller with replaceable blades and more particularly to a propeller specifically adapted for marine use.

In many instances, and particularly when a motor boat is being operated in shallow waters, damage is often inflicted upon the propeller blades of the propeller of the motor boat. Not only can shallow water increase the damage of propeller blades by making it possible for the propeller blades to strike the bottom, but propeller blades can also be damaged by floating or partially floating objects in the water when these objects are struck at high speeds.

When a propeller strikes either the bottom or a sub merged or floating object, one and possibly more of the blades of the propeller are bent or chipped thus greatly reducing the efficiency of the propeller and possibly causing the propeller to be out of balance in which case continued use of the propeller will have adverse effects on the bearings of the propeller shaft to which it is secured.

When one or more blades of a propeller are damaged it would be highly desirable to be able to replace only the damaged blades with new blades so that the expense of a complete new propeller will not be incurred. Additionally, if a means were provided whereby the blades of a marine propeller could readily be replaced, the number of blades on a propeller could be either increased or decreased as desired and the type and pitch of the blades could be varied if additional sets of removable blades were provided. It may therefore be readily understood that a marine propeller constructed in a manner whereby the individual blades thereof may be removed and replaced would be a great advantage.

Accordingly, it is the main object of this invention to provide a marine propeller having removable blades therefor which may be readily replaced when damaged or exchanged for blades of different types when desired.

A further object of this invention, in accordance with the immediately preceding object, is to provide a marine propeller having replaceable blades constructed in a manner whereby the propeller and the blades thereof will have substantially the same structural strength as the conventional type of marine propeller with the blades being formed integrally therewith.

Still another object of this invention is to provide a marine propeller with removable blades which will from all appearances be shaped exactly like a comparable marine propeller having blades formed integrally therewith.

A final object of this invention to be specifically enumerated herein is to provide a marine propeller with replaceable blades which will conform to conventional forms of manufacture, be of simple construction and easy to replace so as to provide a device that will be economically feasible, long lasting and readily adaptable to various environments.

These together with other objects and advantages which 3,132,698 Patented May 12, 1964 stantially upon a plane passing through the longitudinal centerline of the hub of the propeller, parts of the outboard motor lower unit being broken away;

FIGURE 3 is a vertical transverse sectional view taken substantially upon the plane indicated by the section line 3-3 of FIGURE 1 on somewhat of an enlarged scale and with parts of the propeller being broken away;

FIGURE 4 is an exploded perspective view of the propeller; and

FIGURE 5 is a vertical transverse sectional view similar to that of FIGURE 3 but showing a propeller having three removable blades.

Referring now more specifically to the drawings, the numeral 10 generally designates the lower unit of an outboard motor to which the propeller 12 of the instant invention is secured. The lower unit 10 includes a propeller shaft which tapers toward its rear end and is provided with an externally threaded terminal end portion 16. The propeller 12 of the instant invention includes a generally cylindrical hub which is referred to in general by the reference numeral 18. The hub 18 has a tapered opening 20 formed longitudinally therethrough for receiving the tapered end of the propeller shaft 14 with the externally threaded terminal end portion 16 projecting therethrough. The propeller shaft 14 is provided with a keyway 22 and the hub 18 includes a radially inwardly directed and longitudinally extending key 24 receivable in the keyway 22 for locking the hub 18 for rotation with the propeller shaft 14.

The propeller 12 also includes a plurality of blades each generally designated by the reference numeral 26 which are circumferentially spaced about the hub 18. Each of the blades 26 includes a panel-like shank portion 28 terminating at its inner end in an elongated base portion 30 and at its outer end in an enlarged blade portion 32. Each of the blades 26 is gradually twisted about its longitudinal axis from the inner end of the shank toward the free end of the blade portion 32 thereof.

Each of the base portions 30 is generally truncated cone shaped in cross-section and includes oppositely inclined side surfaces 34. The hub 18 includes a plurality of keyways 36 formed in the outer surfaces thereof and opening radially and outwardly therefrom. Each of the keyways 36 has a cross-sectional shape complementary to the base portions 30 and the base portions 30 are snugly and slidably received in the keyways 36. With attention now directed ot FIGURE 4 of the drawings it will be noted that the keyways 36 are tapered and inclined relative to the longitudinal axis of the sleeve 18 whereby the shank portions 28 of the blades 26 adjacent the base portions 30 thereof are disposed in planes inclined relative to the longitudinal axis of the hub 18. Inasmuch as the marine propeller is on the order of a screw, it is very important that the surfaces of the blades 26 adjacent the hub 18 are inclined relative to the longitudinal axis of the hub 18 in order that even the innermost ends of the blades 26 will effect axial thrust upon rotation of the propeller 12 about its axis of rotation.

With attention now directed to FIGURE 3 of the drawings it will be noted that each of the keyways 36 also includes substantially parallel outer confronting surfaces 40 which embracingly engage the opposite side surfaces of the shank portions 28 immediately adjacent the base portions 30. It will be noted that inasmuch as the keyways 36 are disposed at an inclination relative to the longitudinal axis of the hub 18, the greatest depth of the keyways 36 is substantially at their mid-portions, which 3 the longitudinal axis of each of the blades 26. The parallel confronting surfaces 45 of the lteyways 36 provide additional support for resisting lateral deflection of the blades on both sides of the intersection of the longitudinal axis of the blades 26 with their base portions 39.

The tapering of the base portions 30 and the keyways 36 provides a forward limit for movement of the base portions 30 within the keyways 36 and the propeller 12 includes a retaining nut assembly generally referred to by the reference numeral 42 having an internally threaded blind bore 44 formed in one end for threaded engagement with the terminal end portion 16 of the propeller shaft 14. The nut assembly l?) includes a washer member 44 secured thereto and for abutting engagement with the rear end of the hub 18. It is to be noted that the peripheral surfaces of the washer 44 form substantial continuations of the outer peripheral surfaces of the hub 18 and that the washer 44 also abuts the rear end of the base portions 3%) for preventing rearward movement of the latter in the keyways 36.

With attention now directed to FIGURE 5 of the drawings there will be seen a propeller generally designated by the reference numeral -36 which is substantially identical to the propeller 12 with the exception that it is provided with three blades 48 each of which is formed similarly to the blades 26.

It is to be noted that the propeller of the instant invention may be provided with four keyways 36 in the hub 13 thereof in order that the propeller could be used with either four blades or two diametrically opposite blades. If two diametrically opposite blades were to be used, the other two keydays could be filled with dummy keys similar to the base portions of the blades 26. Additionally, various types of sets of blades could be provided for a single hub wherein the hub could then be provided with different ty es of blades for diiferent purposes.

The foregoing is considered as illustrative only of the principles of the invention, Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

A propeller with replaceable blades comprising a cylindrical hub portion having a longitudinal opening formed therethrough for receiving an end of a propeller shaft, said openin including means adapted to lock said hub with a propeller shaft for rotation therewith, a plurality of blades, means removably securing said blades to said hub at circumferentially spaced positions there about, each of said blades including a panel-like shank portion extending radially and outwardly from said hub, disposed in a plane inclined relative to the longitudinal axis of said hub portion and terminating in an enlarged blade portion at its outer end, said blades each being gradually twisted about its longitudinal axis from the end of said shank toward the free end of said blade portion to a greater inclination relative to the axis of rotation of said hub, said shank portions each including an inner end base portion extending in the plane of the inner end of said shank, said securing means including means on said hub interlockingly engaged with said base portions, each of said base portions being truncated cone shaped in cross-section with its major width disposed innermost, said securing means including a plurality of circumferentially spaced keyways formed in the outer surfaces of said hub, opening through one end thereof, inclined relative to the longitudinal axis of said hub and or" a shape in cross-section complementary to said base portions so as to snugly and slidably receive the latter, the opposite elongated inclined side surfaces of each of said base portions gradually diminishing in width and convergent toward said other end of said hub, said keyways each being similarly shaped whereby a tapering of the width of the opposite side surfaces of said base portions and the corresponding surfaces of said keyways and the convergence of said side surfaces toward said other end of said hub will effect a double wedging action on said keyways and establish limits for movement of said base portions in said keyways toward said other end of said hub, said keyways each including substantially parallel outer confronting surfaces intermediate their opposite ends gradually decreasing in height toward opposite ends of said keyways, said parallel confronting surfaces embracing the opposite side surfaces of said shank portions immediately adjacent said base portions on opposite sides of the longitudinal axis of, said blades to provide additional support for resisting lateral deflection of said blades, the opposite ends of said hub being of lesser diameter than the mid-portion thereof disposed intermediate the opposite ends of said hub.

FOREIGN PATENTS Great Britain France Mar. 29, 

